that is a image of our digital piano pedal switches (im still at work and they gave me a camera, the fools!)
I have no idea what the part number is as they come as an assembly from a company called n-code (which you wont find anywhere online) but the good news is that they are coming from east of you Europe so its not some funky custom made thing only found in the states
otherwise another common practice is to use reed switches and magnets